


Time Yet

by printers_devil



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alpha Dimitri Alexandre Blaiddyd, Alpha/Beta/Omega Dynamics, Beta Byleth Eisner, Biting, F/M, Female My Unit | Byleth, Fire Emblem: Three Houses Blue Lions Route, Knotting, Mating Cycles/In Heat, Objectification, Past Underage, Pre-Timeskip | Academy Phase (Fire Emblem: Three Houses), Teacher/Student
Language: English
Status: Completed
Published: 2020-07-19
Updated: 2020-07-19
Packaged: 2021-03-04 20:02:09
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,561
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25212103
Author URL: https://archiveofourown.org/users/printers_devil/pseuds/printers_devil
Summary: Alpha Dimitri goes into rut at the most inconvenient time possible: on the way back from the Blue Lions' mission at Conand Tower. Byleth does her duty as a professor and as a beta.A kink meme fill.
Relationships: Dimitri Alexandre Blaiddyd/My Unit | Byleth
Comments: 4
Kudos: 174
Collections: FE3H Kink Meme





	Time Yet

**Author's Note:**

> Here's the prompt: 
> 
> _Pre-timeskip, A/B/O AU. Alpha!Dimitri or Claude goes into rut while they're travelling to/from a mission. F!Byleth (omega or beta) decides it falls on her to be Responsible and save the mission (or shield her other students) by letting him take it out on her so it'll end more quickly. She's expecting she easily sidetrack him, stay mostly clothed, and just let him rut against her--but he was nursing a crush that in this state translates to a complete fixation on getting inside her. She finds it way harder to resist than she knows it should be._
> 
> _Bonus points if some of the other students *cough*Sylvain*cough* are eavesdropping from outside the tent._

Annette was the only omega on the mission to Conand Tower, and when she started getting nervous and edgy in a way that couldn't be accounted for by seeing a man turn into a giant beast and then killing him, Byleth took note. Whatever pheromones were in the air didn't affect her, but the signs were clear: one of her alpha students was about to go into rut.

Sylvain didn't seem any different from usual. Mercedes was still smiling easily. That left Dimitri, who'd taken to long silences and distant stares on the way back to Garreg Mach. Before Annette's nerves, Byleth had been sure it was just the stress of having to execute someone he must have known as a child.

"I know what it means to be the only omega," Annette said when Byleth came to her about it, drawing herself up to her full height. "If I have to, I'll—"

"You won't," Byleth said, "and you'll never have to, as long as I'm your teacher."

A shadow crossed Annette's face as she took those words in. Noble omegas of breeding age with Crests likely didn't hear those words very often— _You don't have to_ —and Annette had mentioned that her uncle the baron was very hard on her. Well, that was what betas were for, or else every omega in the world would be stuck on some alpha's knot, and no one would get anything done.

Byleth went to Dimitri next. He'd made his own fire at the edge of camp, and he frowned into it. His lance sat against the tree, and he hardly glanced up at her, even when she deliberately broke a stick underfoot to signal her approach.

"I know," Dimitri said, before she could open her mouth. "It's coming. I can keep it under control until we get to the monastery, professor."

She frowned, and Dimitri looked up at her, shamefaced.

"I can," he insisted. "Please, don't concern yourself with me."

"Very well, then," Byleth replied, and left him.

If it got back to Seteth that one of her alphas had gone into rut in the middle of a mission and harmed someone, Byleth would never hear the end of it. She kept an eye on him, and to had a word with the class's betas, too.

Dedue nodded and promised not to leave His Highness's side. Ingrid looked very serious said something about her duty to to the crown. Felix, who had no patience for alphas and their cycles, merely sneered about stupid animals being unable to control themselves. He went on in that vein for a while until Byleth brought up Annette, at which point he'd looked irritated, but said he could watch over Annette, at least.

But there were still days to go before they made it back to the monastery. No one could keep watch on Dimitri the whole time. When they stopped in towns for the night, it was easier; she locked Annette in a room with Ingrid and took the room next to Dimitri's. When they and the Knights made camp, however, it was more difficult. As the ranking knight, Catherine made the patrol roster, and that roster separated Byleth's students for hours on end.

And so, when they were two days out from the monastery, Byleth walked through camp on her own, just to check. Dedue was out on watch, sweeping the forest on the opposite side of the camp. Dimitri's tent was pitched at the edge of the cleaning, and the full moon gave Byleth just enough illumination to see that its walls were moving suspiciously.

Being nervous was new to her, but she was reasonably sure that was what she was feeling. Sothis had been sleeping since the Miklan had become the Black Beast, and if she was awake, she would have been saying, _What kind of beta are you, letting things come to this? An embarrassment! Can you do nothing on your own?_

Byleth eased the tent's flap open, just a sliver. The smell of sex hit her immediately. Dimitri's kit was perfectly laid out along the tent wall, his lances ordered by height and his uniform folded atop his pack. On the bedroll, Dimitri lay atop of Annette's little body, his face buried in her neck, inhaling her scent in deep, trembling breaths. Byleth could hardly see Annette beneath him, but she writhed beneath him, moaning. "Please, Dimitri," Annette said, and she kept babbling, "please, please, please, I need you," until it was just sound.

"You want me inside you?" Dimitri asked. He sounded cordial, but his voice was low and heavy. He was near-unrecognizable as Byleth's polite prince, with his shirt discarded and his hair mussed from where Annette must have been grabbing at it. One of his legs was jammed up between Annette's thighs. He'd torn Annette's tights open, and she moved desperately beneath him, rubbing herself against his trouser leg. "Will you take my knot, Annette?"

The sight was arresting. Byleth, who should have been much better than this, paused for a moment to appreciate it, the way Dimitri's body dwarfed Annette's smaller frame, how Dimitri's muscular body moved. However, she'd made a promise. A promise was a contract.

She strode into the tent and seized Dimitri by the back of the neck. Alphas did this to each other in dominance displays; fortunately, their necks didn't know when a beta was doing it. Dimitri froze and tried to turn around to see what had interrupted him, but Byleth held him fast, forcing him up and off of Annette. He strained against Byleth's hand, but she held him harder, her thumb pressing into the base of his skull. Every nerve in his body would be telling him to submit to her. It was useful, but it never lasted long.

"Please get out of the tent, Annette," Byleth said.

Annette gaped up at the two of them. Dimitri tried to escape her grip once more, and she took his arm and wrenched it behind his back.

"But professor, I want it," Annette whined, grasping after Dimitri. Her other hand was inside her little white panties, rubbing slowly at herself. "I _want_ it—"

"His scent is making you want it," Byleth said. "You don't have to do this. Go find Felix or Ingrid."

Annette shivered visibly at the command in Byleth's voice and got to her feet. Her movements were jerky, and her eyes were on Dimitri the whole time—she really was in heat. Somehow, Dimitri's rut had dragged her out of cycle. She'd known Dimitri was a strong alpha, but not _that_ strong.

But Annette smoothed down her uniform skirt, then left the tent, her eyes on Dimitri the entire time. The skirt did not entirely cover her ripped tights, and Byleth could only hope no one came across her between this tent and a classmate.

Annette could be trusted to keep her mouth shut, at least. That only left Dimitri's rut to take care of. She'd had to talk down alphas before as a mercenary. It had just been a chore the company's betas had done, no different in her eyes than cooking or laundry; even Jeralt had pitched in to help. All she had to do was let him hump her leg a bit and get it out of his system.

Only when she could not smell Annette anymore did she release Dimitri's neck. Dimitri shook his head hard. He glared at her, his eyes startlingly blue even in the dim light. Then he lunged forward and brought Byleth down to the ground in one efficient motion. She landed hard on her back, the impact jarring her neck and making her wince.

Dimitri covered her as soon as she was down, pressing her hard onto his bedroll with all his weight. His school uniform made him look deceptively slight, but he had a wonderful set of shoulders. His skin was hot, burning, even through all her clothes.

Byleth tested his hold on her, trying to find an avenue of escape, but there was nowhere to go. He'd been taught well.

"Annette is mine, professor," Dimitri said into her ear. "I marked her."

"No. She's your classmate. I'm here now to take care of you." Byleth guided his head to her neck. "I'm here for you."

There was nothing for him to smell there, but he inhaled her anyway. Just his breath against her her skin sent trails of sensation through the rest of her body. He kept his mouth there, teasing her, grazing her with just the tips of his teeth for an interminably long time, before he sank them into her flesh, biting hard.

No alpha she'd talked down had ever dared do this to their captain's daughter. His teeth broke skin. She cried out, so loudly anyone walking by the tent might have heard her. The pain was a violent jolt to her senses; his pheromones filled the tent, and they smelled amazing. She brought her leg up between his as his had been between Annette's, pushing her thigh against his hard cock, and he pressed into her, making a low sound into her skin.

Byleth squirmed under Dimitri as he pulled away, licking at the raw, throbbing bite mark on her neck. "I apologize," he said, sounding more like himself for the moment. "But—ah, professor—I need you."

He did not give her time to answer. With surprising coordination for an alpha in rut, he shoved her shirt up so that the fabric was bunched under her chin, freeing her breasts. He kissed and sucked at them, marking them all over, and he looked so intent, as though the only thing in this world that mattered was pleasuring her. She was going to be covered in bruises. There was time yet to stop this going too far. 

Then he bit one her nipples too hard, and Byleth hissed with pain. His tongue was there once again to soothe it. She was going to be bruised all over by the time he was finished. All the while, his cock rubbed steadily against her leg. Byleth moved with him, helplessly. When she'd been a mercenary, she'd simply lain back and let this happen.

"I—I want to breed you, professor," Dimitri said against her mouth, as though he could not bear to pull away from her. "Please. I'll make it good for you, I promise."

She huffed out a sigh against him. She'd been killing since she could hold a weapon, and she'd been doing a beta's duty since she was a bit younger than Dimitri, if she was correct about her own age. If she was old enough to kill, she was old enough to do this, she'd said, when Jeralt had tried to forbid her from it. And it always, always went like this: there came a point at which an alpha would say anything to get inside any hole at all, so long as it was wet, or could be made wet. She said no, and they'd rarely had the presence of mind to argue the point further. They came against her, and then it was done. No one spoke about it the next day. It was impersonal. 

Not Dimitri. There was adoration in his eyes. Above her, he paused his rutting, and he made a pained noise. He came up suddenly to kiss her, hungry and hard, catching her lower lip between his teeth. No longer satisfied with her thigh—apparently—he parted her legs so he could seat himself between them, and the hard ridge of his cock pressed against directly against where she was most sensitive.

She was not the victim of a mating cycle. She could simply knock him out and leave. And yet, a cloud must have moved over the moon, because it was suddenly much darker in the tent; in this darkness, anything seemed possible. She pushed back against him as he fucked her through their clothes, winding her legs around his hips, holding him against her.

He pressed his lips against the bite on her neck, and it was still raw and throbbing under his touch. He kissed it, over and over, and a warmth filled her, from the tips of her toes, to where he was rubbing himself off on her, to her abused breasts pressed against the smooth skin of his chest. She was going to go mad from this. It was impossible for his scent to cloud her judgment, but his weight moving atop her, the greedy sounds he made as he put more bruises on her neck, turned her mind to putty.

"Dimitri," she gasped, after one particularly hard thrust set the seam of her shorts pressing against her clit. She tried and failed to rally her thoughts into some semblance of order. "Go ahead. It's all right."

It was still dark. Byleth felt him pull her shorts and tights off without tearing them: even deep in his rut, he was such a considerate boy. He had not seemed so considerate with Annette, but that was far away, a problem for the future. She had fought him hand-to-hand before and knew precisely how strong he was, but having a demonstration of his restraint between her legs, his knuckles passing over her clit as he tested her wetness, was different. It sent a shiver up her spine.

His cock was out of his thin trousers and pressed against her entrance moments later. He thrust it easily through her folds once, then twice, exhaling hard against her neck. She put her own hand between her legs, stroking her clit while he teased her, gauging her readiness. Young, powerful alphas like Dimitri could go forever, which was less of a problem when they were humping her thigh and begging to come anywhere she'd have them. Byleth was not as wet as an omega might have been, but she was ready to take him.

Dimitri knocked her hand aside and left his cock pressed between her folds, just barely. The other hand pressed her hip down so she couldn't drive herself against him.

"May I put it in?" he asked, his voice ragged with desire.

Byleth looked sternly up at him and seized his cock to line it up with her cunt. It was so thick in her hands, she could not imagine how big his knot was going to feel. The moon had come out once more, and she could discern his features in shadow: the way his mouth dropped open in surprise when he pressed the tip into her, the way he blinked rapidly, as though stunned, when he seated himself fully inside her.

He moved slowly in her. She tried to meet him stroke for stroke, but that hand was at her hip again, making movement impossible. That only made it worse—better. She didn't know. His cock stretched her wide, the head of him catching at her entrance every time he nearly pulled out.

It was maddening. She whimpered underneath him, her heels digging into the small of his back, trying to keep him inside, but it did not work. Her nails bit into the skin of his back, and she made herself tight around him, trying her best to entice him to fuck her harder, faster, do anything but use her as a sleeve to work out his lust on.

Dimitri was her student and her soldier. He followed her orders. She was the Ashen Demon, not some delicate omega who could only lay here beg for him to knot her. She took his face in both of her hands, forcing him to meet her eyes.

"Dimitri," she said firmly. "Don't waste my time. Fuck me."

In the light of day, Byleth surely would have seen him blush. Even his rut could not change who and what he was, not around her. In a few neat movements, Dimitri turned her over onto her belly and shoved into her, his hand on the back of her neck pinioning her in place. His mouth returned to the bite mark, licking at it, nuzzling it.

"At your order, Professor," Dimitri murmured.

He set a hard, punishing pace. She could not think of anything outside of this tent, not what people would think of the mark he'd left on her, not how Annette was faring, not Seteth's inevitable lecture about her failure as a teacher. There was only his scent, enveloping her—the bead of his sweat that dropped into the center of her back. He groped at her breasts, sliding a hand across her chest with an impatient touch as he fucked her.

It was overwhelming. That she'd thought she could lay indifferently beneath him seemed like a far-off joke. Dimitri's thrusts became short and vicious as he began thickening inside her. Byleth's eyes flew open. Her cunt not made to take an alpha's knot. She'd never allowed it, never tried it, for good reason—was this panic? It felt like panic.

She tried to get away from him, but he held her fast, dragging her hips back onto his as he chased his own pleasure. Without a pause, without so much as missing a beat, Dimitri forced her upright so that she stood on her on her knees. Her head tipped back onto his shoulder, and she could see his face again, his handsome, boyish features contorted with desire, his damp golden hair stuck to his forehead.

"Professor, I'm going to come inside of you," he said into her ear, drawing her back and forth on his cock.

Byleth gave him a very slight nod: he couldn't make her pregnant, she had nothing to fear there. There was just the knot to get through. He groaned so softly it was almost a sigh, and his hips stuttered in their rhythm.

She felt a wet rush as he spent inside of her, and she braced herself for what came next. Omegas survived this all the time, it couldn't be that bad. His knot expanded, swelling to fill her up painfully, almost to bursting, and she cried out in shock.

"I've wanted to do this for so long," Dimitri said, his strained, his hand going between her legs to play with her clit, rough and slow. "I admire your strength and poise, and you're an able commander and—you are so beautiful—"

Byleth could not have formulated a response. Stuffed full of him like this, the pleasure was overwhelming. She shifted from side to side, trying to find any friction at all, and found herself stuck in truth. Her knees gave out, and she slumped forward, Dimitri following her to rest against her back, breathing hard, as he rubbed her off. Her orgasm came swiftly, a bolt of fire that passed through her and left her scoured out, blinded, gasping mutely for air.

She lay beneath him, limp and spent. Her cunt twitched with the aftershocks of it, as though it could milk more come out of Dimitri. Gradually, his knot deflated.

He sighed, then rolled off of her and gazed adoringly into her eyes. If she had a pulse, it might have kicked up. She could not encourage this behavior. If Sothis woke up to Dimitri following Byleth around, mooning over her, she would never let her live it down.

 _Ridiculous!_ Sothis would say. _He is magnificent! Why, had I a body of my own, I would throw caution to the wind and have my way with him as often as I liked! What is stopping you, foolish child?_

"You will run ten laps around the monastery when we return," Byleth said. "You will write a letter of apology to Annette."

"Yes, professor," Dimitri said meekly.

"And you will never lose control of yourself like this again," she added.

He looked so solemn and contrite that Byleth had to kiss him—very chastely, on his sweaty forehead, as though his come would not be running out of her as soon as she stood up. She found her shorts. Sothis stirred in the back of her mind, which was as strong an argument as any for returning to her tent as quickly as possible.

"I expect to see you at breakfast," Byleth said. "Have a care for your health."

"I shall," Dimitri said. Before she could stand and leave, however, he yanked her down into a hot, seeking kiss.

She had seen him through the worst of his rut. Kissing him on the mouth again could not hurt anything. Byleth gave in to the kiss for several moments longer than she needed, dressed, and did not notice until she was halfway across the camp that she had left her tights and underwear behind in Dimitri's tent—checking on Annette would have to wait, then.

It was still dark out. The embers of the cookfire were banked and low. Dedue and the Knights were returning from their patrol, and Annette's tent was still and quiet. All was well.

And then Sothis woke up, manifesting next to Byleth as she walked, peering at Byleth's neck.

 _My, my, my, you have been busy, my beta friend!_ Sothis said, her sweet voice ringing out like a bell in the night. _Come, tell me all about this mark._

Byleth sighed, and prepared herself for a long trip back to the monastery.

**Author's Note:**

> Somewhere in here there's a spin-off fic about Annette going to Felix "absolutely no patience for this abo shit, oh my god, please can we just get through sword drills without someone going into heat" Hugo Fraldarius to get talked down... maybe someday. Find your pal PD on twitter at [a_printersdevil](https://twitter.com/a_printersdevil).


End file.
